Fix Chrome autocomplete incorrectly triggerring actions

[MatheusRich]

When using a Stimulus action like

<button data-action="keydown.meta+k@window->search#open">

in Google Chrome, clicking an input's autocomplete suggestion unexpectedly triggers the controller action even though no key is pressed.

It seems that Chrome dispatches an Event with type === "keydown", but it is not an instance of KeyboardEvent. This happens regardless of the key filter.

Closes #852

[seanpdoyle]

@jorgemanrubia are you able to enable this PR's CI workflow?

[seanpdoyle]

The underlying Action.shouldIgnoreKeyboardEvent function ultimately accesses properties on the KeyboardEvent instance, so instantiating a new KeyboardEvent instance without those properties might lead to unexpected behavior.

As an alternative, what do you think about using typecasting instead?

Suggested change

	if (event.type === "keydown") {
	// when accepting an autocomplete suggestion, Chrome dispatches a keydown event,
	// but it isn't a KeyboardEvent instance
	const keyboardEvent: KeyboardEvent = event instanceof KeyboardEvent ? event : new KeyboardEvent("keydown")
	if (this.action.shouldIgnoreKeyboardEvent(keyboardEvent)) {
	// When accepting an autocomplete suggestion, Chrome dispatches a keydown event that is not a KeyboardEvent instance
	if (event.type === "keydown" && this.action.shouldIgnoreKeyboardEvent(event as KeyboardEvent)) {

That assumes that Chrome's synthetic event does have the properties required to behave like a KeyboardEvent. That might not be the case, but my hunch is that it'd behave better as the syntetic event than as an event that Stimulus constructs itself.

[MatheusRich]

My intention was to use a newly created keyboard event where all of those keys are blank (so nothing matches). Typecasting probably works, but that synthetic event doesn't have any of the KeyboardEvent properties (besides type). The code would be a lot cleaner, though.